It is taken into the body in water and foods. People use it for medicine.

Selenium is used for diseases of the heart and blood vessels, including stroke and “hardening of the arteries” (atherosclerosis). It is also used for preventing various cancers including cancer of the prostate, stomach, lung, and skin.

Selenium is also used for preventing serious complications and death from critical illnesses such as head injury and burns. It is also used for preventing bird flu, treating HIV/AIDS, and reducing side effects from cancerchemotherapy.

you may find that you don’t have enough motivation; most people have high enthusiasm initially which, when confronted with the challenges of learning programming, goes away bit by bit until it is over ; so one of the risks is that you start learning, then stop it and feel like you failed

you may realize while learning Selenium that you like it so much that you dont want to do manual testing any longer; i know people who after learning some automation did not want to go back; so another risk may be that your manual testing days are over but your automation days are started

you may get to a point where you will be willing on learning Selenium and programming not only during your work hours but also at home; so you will be risking some of your free time (and your family’s)

you may be risking some of your friendships if you make progress with your automation learning; some of your tester friends who cannot do it may not be positively impressed by you doing what they cannot

finally, you may be risking your career and your job; when you learn enough programming and automation, you may stop being a tester and become a developer; you lose your tester job but gain a developer one